No abstract

A field experiment was conducted to assess the effects of drip fertigation with biofertilizers on growth, yield, water, and fertilizer-use efficiency of Bt cotton. The treatments were comprised of drip fertigation with 75, 100, 125, and 150% of recommended dose of fertilizers (RDF) combined with and without biofertilizers as biofertigation, soil application of 100% RDF, and control. Growth, yield attributes, water, and fertilizer-use efficiency of Bt cotton were significantly influenced by drip fertigation treatments. Application of 150% nitrogen (N)-phosphorus (P)-potassium (K) as drip fertigation combined with biofertigation of liquid formulation of azophosmet at 250 ml (10 12 cells ml −1 ) ha −1 was significantly superior over surface irrigation and soil application of 100% NPK and registered the greatest seed cotton yield of 3395 kg ha −1 . The soil fertility status was greater under this treatment when compared to surface irrigation and soil application of fertilizers. It is recommended that drip fertigation of inorganic fertilizers in combination with biofertigation be used as a viable technique to realize the yield potential of Bt cotton and sustenance of soil fertility.

Water stress induces some physiological changes in plants and has cumulative effects on crop growth and yield. Field experiments were conducted to study the effect of deficit irrigation (DI) on yield and some physiological parameters in cotton and maize in a sequential cropping system. Creation of soil moisture gradient is indispensable to explore the beneficial effects of partial root zone drying (PRD) irrigation and it could be possible only through alternate deficit irrigation (ADI) practice in paired row system of drip layout that is commonly practiced in India. In the present study, PRD and DI concepts (creation of soil moisture gradient) were implemented through ADI at two levels of irrigation using drip system. Maize was sown after cotton under no till condition without disturbing the raised bed and drip layout. Relative leaf water content (RLWC) and chlorophyll stability index (CSI) of cotton and maize were reduced under water stress. A higher level of leaf proline content was observed under severe water-stressed treatments in cotton and maize. RLWC and CSI were highest and leaf proline content was lowest in mild water deficit (ADI at 100% crop evapotranspiration once in three days) irrigation in cotton and maize. The same treatments registered higher values for crop yields, net income and benefit cost ratio for both the crops.

The assessment of water use efficiency and crop performance of cotton–maize cropping sequence under deficit irrigation has not been thoroughly studied in India. Field experiments were conducted at the Agricultural College and Research Institute, Coimbatore, during 2007–2009 to study the effect of deficit irrigation practices through a drip irrigation system on crop productivity, and the water use efficiency of cotton–maize cropping sequence. Experimental treatments comprised of six irrigation levels (full and deficit) through a drip system, with surface irrigation as one of the treatments for comparison. Maize was sown after hybrid cotton, under no‐till conditions, without disturbing the raised bed and drip layout. Among deficit irrigation practices, mild deficit (ADI at 100% ETc once in three days) registered higher values for seed cotton yield (3670–3760 kg ha‐1), grain yield of maize (7420–7590 kg ha‐1) and water use efficiency (9.0 and 18.0–20.4 kg ha‐1 mm‐1 for cotton and maize, respectively). A significant second‐degree polynomial relationship between crop yields and water use (WU) was found for both the crops. Copyright © 2011 John Wiley & Sons, Ltd.

A field investigation was carried out at Agricultural Research Station, Bhavanisagar of Tamil Nadu Agricultural University, during kharif 2009 and 2010 to evaluate the new formulation of oxyfluorfen (23.5% EC) on weed control in onion and their residual effect on succeeding crops. Based on two years field experimentation, it was found that pre-emergence application of oxyfluorfen (23.5% EC) at 400 g ha-1 gave significantly lower total weed density, weed dry weight and higher weed control efficiency at all the stages. Application of new formulation of oxyfluorfen (23.5% EC) at 200 g ha -1 as pre-emergence herbicide kept the weed density and dry weight below the economic threshold level and increased the bulb yield (15940 and 15610 kg ha -1 ) in onion. Succeeding crops like sunflower and pearl millet sown immediately after the harvest of onion was not affected by the residue of new formulation of oxyfluorfen at all different doses.